1. Field of the Invention
The present invention relates to an inverter circuit using insulated gate field effect transistors and more particularly to a high voltage inverter circuit for generating a high voltage pulse train in response to a low voltage input, at the voltage level of electronic circuits using insulated gate field effect transistors. Hereinafter, insulated gate field effect transistors are referred to as MOS (Metal-Oxide-Semiconductor) transistors which are representative of the insulated gate field effect transistors.
An example of use for such a high voltage inverter circuit is a generator of high-voltage and high-frequency pulses for driving an alternating current (AC) drive type plasma display panels, an electrostatic printing devices, or the like. An inverter circuit using the MOS transistors will be briefly referred hereinafter to as a MOS inverter.
2. Description of the Prior Art
A discharge cell of an AC plasma display panel requires a relatively high initial firing voltage. For instance, high pulse voltages of 250 to 300 volts must be applied to a gas discharge cell. Especially, for the AC drive type of plasma display panel to be driven in a scanning mode, the drivable electrode number and brightness are determined by the frequency of the applied drive pulses. In such an operation, therefore, a pulse generating circuit or inverter circuit to generate a high voltage and high speed pulse train is indispensable.
Since it has conventionally been difficult to obtain anything other than a bipolar transistor which may be used as a high voltage transistor, bipolar transistors have been used in almost every circuit for driving an AC type plasma display panel. However, the high voltage bipolar transistor has many drawbacks such that an operating speed is restricted due to the minority carrier storage effect, and a second breakdown is liable to occur. Assuming that such bipolar transistors are used for an inverter circuit to generate a high-voltage, high-frequency pulse train having a frequency higher than 500 KHz at a voltage of 250 to 300 volts, it is difficult to mass produce it in a satisfactory yield and at a low cost. Recently, various efforts have been made to increase the drain breakdown voltage of the MOS transistor. High voltage MOS transistors have been obtained which can stand a voltage higher than 200 to 300 volts in either the N-channel or the P-channel. Such high voltage MOS transistors are disclosed in U.S. Pat. No. 4,172,260 issued to Takeaki Okabe et al. on Oct. 23, 1979. The MOS transistor is found to be promising as a high voltage circuit element because it has a high operating speed and a high voltage circuit element because it has a high operating speed and a high breakdown voltage due to its negative temperature characteristics with respect to current. Thus, it is desirable to use a MOS inverter for high voltage and high frequency applications, in place of the conventional inverter circuit employing bipolar elements.